Drainage composition and uses thereof

ABSTRACT

A drainage composition comprising 1000 to 1500 kg/m3 of aggregate; 100 to 350 kg/m3 of cement; 0 to 100 kg/m3 of fly ash; and 0.2 to 0.6 kg/m3 of fibrous material.

RELATED APPLICATIONS

This application corresponds to PCT Int'l Appln. PCT/AU03/00475, filedApr. 22, 2003, and claims priority to Australian Provisional PatentAppln. Ser. No. PS 1894, filed Apr. 22, 2002, the subject matter ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to a drainage composition and uses thereof. Inparticular, the invention relates to providing drainage for a retainingwall. However, it should be appreciated that the drainage compositionmay be used for other drainage purposes.

BACKGROUND OF THE INVENTION

Retaining walls are a common method of retaining soil. The requirementsof a functional retaining wall are structural stability and durabilityagainst the exposed environment and the provision of drainage.

To complete a retaining wall, typically earth is excavated, a block wallor concrete wall is erected, gravel is bagged and stacked adjacent theblock wall, weep holes are located in the wall at various locationsalong the length of the wall, pipes are located through the weep holesto drain any water that passes through the gravel to the base of thewall, and the excavated soil is placed behind the retaining wall.

It is important that the drainage system functions correctly asretaining walls are rarely designed to withstand ponded water pressure.Ponded water pressure can triple or quadruple the loading on theretaining wall if allowed to develop. Often this additional pressurewill cause the retaining wall to fail with serious consequences.

The stacked bags of gravel located behind the wall provide a drainagesystem. However, sometimes a bag may split. The pressure of the earththen spreads the earth through the gravel preventing water from flowingthrough the gravel reducing the efficiency of the drain. If many bagsspit then ponded water may occur which is undesirable.

Another problem with using bagged gravel is that it is very timeconsuming to produce the drainage system. Gravel must be individuallyplaced into bags by shovelling the gravel into a bagging machine. Thebags must then be stacked on top of each other. The making and placingof the bags of gravel usually take considerably more time than theconstruction of the block wall.

OBJECT OF THE INVENTION

It is an object of the invention to overcome or alleviate theaforementioned disadvantages or provide the consumer with a useful orcommercial choice.

SUMMARY OF THE INVENTION

In one form, though not necessarily the broadest or only form, theinvention resides in a drainage composition comprising:

-   -   1000 to 1500 kg/m³ of aggregate;    -   100 to 350 kg/m³ of cement;    -   0 to 100 kg/m³ of fly ash; and    -   0.5 to 0.6 kg/m³ of fibrous material.

The size of the aggregate typically varies from between 10 mm and 75 mmaggregate. Different sized aggregates may be combined in the drainagecomposition.

Preferably, the volume of aggregate to fly ash mixed according toapproximately the ratio of 3:1.

The fibrous material may be fibre. Normally the synthetic fibre is anylon fibre. The nylon fibre may be between 19 mm to 50 mm long.Preferably, the amount of fibrous material used is between 0.4 to 0.6kg/m³.

The drainage composition may be made into blocks, panels or may bepoured freely such as in the case of a slab.

The drainage composition may be formed adjacent other structures such aspanels or blocks.

Sand may be added to the composition. The weight of sand may between 40to 200 kg/m³.

In another form, although not necessarily the broadest or only form, theinvention resides in a retaining wall comprising:

-   -   a load bearing structure to retain earth; and    -   a drainage structure located adjacent said load bearing        structural;    -   wherein water is able to flow through said drainage structure.

The load bearing structure may be in the form of blocks or panels and/ormay be poured freely to form a load-bearing wall.

The drainage structure may be formed from blocks, panels and/or pouredfreely.

The load being structure and drainage structure may be contiguous.

A geofabric may be located adjacent said drainage structure.

In another form, although not necessarily the broadest or only form, theinvention resides in a roadway comprising:

-   -   a road contact layer on which traffic travels and    -   a drainage layer located adjacent said road contact layer;    -   wherein water is able to flow through said drainage layer.

The road contact surface is normal tar, asphalt, concrete or the likematerial. It is usually laid directly onto the drainage layer.

The drainage layer may be formed from blocks, panels and/or pouredfreely.

A geofabric may be located adjacent said drainage structure.

In another form, the invention resides in erosion prevention systemcomprising:

-   -   a drainage structure;    -   soil located on top of said drainage structure; and    -   a multiplicity of plants located within said soil    -   wherein a root system of said plants passes through the soil and        extends into said drainage structure.

The drainage structure is usually preformed blocks or panels. However,the drainage structure may be laid in situ.

Typically, the plants that are used are a form of grass.

In another form, the invention resides in a weir comprising:

-   -   a drainage wall that forms a dam to capture water, said drainage        wall allowing water to pass through said wall; and    -   a filter material located adjacent said drainage wall to filter        impurities located within said water.

The drainage wall is usually constructed from preformed blocks orpanels. However, the drainage composition may be laid in situ.

The filter material may be a geotextile.

In another form, the invention resides in a block comprising:

-   -   a face layer and    -   a drainage layer,    -   said face layer being integrally formed with said drainage        layer.

The face layer may be formed from concrete, sandstone, clay or the likematerials.

Typically, said face layer is thinner than said drainage layer.

In one form, though not necessarily the broadest or only form, theinvention resides in a drainage composition comprising:

-   -   1000 to 1500 kg/m³ of aggregate;    -   100 to 350 kg/m³ of cement;    -   0 to 100 kg/m³ of fly ash; and    -   5 to 100 kg/m³ of metal filament material.

Preferably, the metal filament material is steel. More preferably, thesteel is stainless steel.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention, by way of example only will now bedescribed with reference to the accompanying drawings in which:

FIG. 1 a sectional side view of a retaining wall according to a firstembodiment of the invention;

FIG. 2 is a sectional side view of a retaining wall according to asecond embodiment of the invention;

FIG. 3 is a sectional side view of a retaining wall according to a thirdembodiment of the invention;

FIG. 4 is a sectional side view of a retaining wall according to afourth embodiment of the invention;

FIG. 5A is a top view a panel according to an embodiment of theinvention;

FIG. 5B is a sectional side view a panel according to FIG. 5A;

FIG. 6A is a sectional side view of a proposed roadway; and

FIG. 6B is a sectional side view of a roadway according to an embodimentof the invention.

FIG. 7 is a sectional side view of an erosion prevention systemaccording to an embodiment of the invention;

FIG. 8 is a sectional side view of a weir according to an embodiment ofthe invention; and

FIG. 9 is a perspective view of a block according to an embodiment ofthe invention.

DETAILED DESCRIPTION OF PREFFERED EMBODIMENTS

FIG. 1 shows a retaining wall 10 comprising a load bearing structure 20,drainage structure 30 and a length of geofabric 40.

The loading bearing structure 20 is constructed from a series ofconcrete blocks 21. A weep hole (not shown) is located in approximately10 percent of the concrete blocks 21. It should be appreciated that theloading bearing structure is known and that a person skilled in the artwould be aware of the techniques needed to produce the load bearingstructure.

The drainage structure 30 has been constructed from a series of drainageblocks 31. Each drainage block 30 has been produced from a drainagecomposition that uses the following ratio of components:

-   -   1200 kg/m³ of 20 mm aggregate;    -   220 kg/m³ of cement;    -   60 kg/m³ of fly ash; and    -   0.4 kg/m³ of fibrous material.

The composition was mixed with water in a standard manner and soliddrainage blocks 31 of dimensions of 600 mm×300 mm×300 mm were producedusing standard techniques. The drainage blocks 31 produced allowed waterto flow through them. A weep hole 41 was produced in approximately every10 percent of the drainage blocks 31.

The retaining wall was constructed by firstly excavating earth 50adjacent to where the retaining wall was to be placed. The first tworows of concrete blocks 21 were then laid and attached to each otherusing mortar. The drainage blocks 31 were then laid without the use ofmortar. Pipes 42 were located through the weep holes 41 along the lengthof the retaining wall 10. Geofabric 40 was placed under the first courseof drainage blocks to hold it in position. The excavated earth 50 wasthen back filled. This process was repeated until the retaining wall 10was completed.

The drainage blocks 31 are porous. Hence any water that travels throughthe earth 50 passes through the geofabric, through the drainage blocks31 until the water finally passes through the respective pipes 42. Thegeofabric prevents the earth 50 from directly contacting the drainageblocks 31 and thereby reducing their effectiveness by partially blockingholes located within drainage blocks 31.

The time saved by using the drainage blocks 31 is substantial. Further,the drainage blocks 31 resist deterioration increasing the overalllifespan of the retaining wall 10.

The drainage blocks 21 of FIG. 1 were also produced from a drainagecomposition that uses the following ratio of components:

-   -   1200 kg/m³ of 20 mm aggregate;    -   220 kg/m³ of cement;    -   60 kg/m³ of fly ash; and    -   20 kg/m³ of stainless steel filament material.

The blocks that were produced were of substantially the samecharacteristics and performed substantially the same function as theblocks made with nylon fibres.

FIG. 2. shows a similar type of retaining wall as disclosed in FIG. 1.However, the concrete blocks 21 have been replaced by stones 22 adheredtogether with mortar. The mortar also adheres the stones 22 to thedrainage blocks 31 to form an integral retaining wall 10. This increasesthe overall strength of the retaining wall 10.

FIG. 3 again shows a similar retaining wall to that disclosed in FIG. 1.In this embodiment, drainage panels 32 have replaced the drainage blocks31.

The drainage panels 22 were constructed from a drainage composition thatuses the following ratio of components:

-   -   1200 kg/m³ of 10 mm aggregate;    -   230 kg/m³ of cement;    -   45 kg/m³ of fly ash; and    -   0.45 kg/m³ of fibrous material.

FIG. 4 shows a similar embodiment of a retaining wall as that disclosedin FIG. 3. In this embodiment, the drainage panels 32 are the same.However, the concrete blocks 21 have been replaced by a concreteload-bearing wall 23. The load-bearing wall 23 was formed by sprayingconcrete (known as ShotCrete) over metal reinforcing 24. The metalreinforcing 24 is tied to metal reinforcing 61 located within a footing62.

The sprayed concrete sticks directly onto the drainage panels 32 toproduce a stronger retaining wall 10.

Gravel 60 has also been located between the geofabric and earth toassist in the flow of water through the earth and through the geofabricinto the drainage panels 32.

FIGS. 5A and 5B shows a prefabricated panel 100 for a retaining wallcomprising a load bearing section 110 and a drainage section 120.

The load bearing section 110 is constructed from concrete 111 that covermetal reinforcing 112. Lifting lugs 113 are located within the loadbearing section so that the panel can be lifted into a desired location.

The drainage section is constructed from a drainage composition thatuses the following ratio of components:

-   -   1200 kg/m³ of 20 mm aggregate;    -   200 kg/m³ of cement;    -   65 kg/m³ of fly ash; and    -   0.35 kg/m³ of fibrous material.

A metal tie 130 assists in holding the load beading section 110 and thedrainage section 120 together. Geofabric (not shown) may be placed overthe drainage section 120 if desired. A pipe 131 is placed through theload bearing section 110 into the drainage section 120.

The prefabricated panel 100 may be used to quickly and easily constructa retaining wall 100. After excavation of earth, the prefabricated panel100 only needs to be fixed in position using a footing (not shown). Theearth can then be back filled to produce a retaining wall.

FIG. 6A shows a proposed location for a roadway 201. Along the proposedpath is wet area 202 where water passes through the earth 203.

FIG. 6B shows the roadway 200, after completition, which extends throughthe wet area 203. The roadway 200 comprises an asphalt contact layer210, drainage layer 220 and geofabric 230.

The asphalt contact layer 210 is standard road base. It should beappreciated that the asphalt contact layer 210 may be replaced withconcrete depending on the amount of water that flows through the wetarea.

The drainage layer 220 is constructed from a drainage composition thatuses the following ratio of components:

-   -   1300 kg/m³ of a mixture of 10 and 20 mm aggregate;    -   190 kg/m³ of cement;    -   55 kg/m³ of fly ash; and    -   0.55 kg/m³ of fibrous material.

The roadway 200 is constructed by excavating earth 203 at the wet area202. The geofabric 230 is then laid within the excavation. The drainagecomposition is then poured into the excavation until it covers the wetarea 202 to form the drainage layer 220. The asphalt contact layer 210is then laid on top of the drainage layer 220.

The drainage layer 220 allows water to pass through the wet area 202without water passing through the surface of the asphalt contact layer210. Hence, improved roadways 200 can be produced more efficiently andeffectively.

FIG. 7 shows an erosion prevention system 300 produced using theincorporated drainage blocks 310.

The drainage blocks 310 are produced from a drainage composition usingthe following ratio of components:

-   -   1250 kg/m³ of 20 mm aggregate;    -   270 kg/m³ of cement;    -   75 kg/m³ of fly ash; and    -   0.5 kg/m³ of fibrous material.

To produce the erosion prevention system, the drainage blocks 310 areburied within the soil 320. Grass seed is then spread on top of the soil320. When the grass seed sprouts and commences growing, a root system331 of the grass 330 penetrates the soil and also penetrates thedrainage blocks 310 to complete the erosion prevention system. Thisrooting of the grass within the blocks 320 provides a firm anchor forthe soil 320 and hence prevents erosion.

FIG. 8 shows a weir 400 that is used to filter impurities from waterused in industry such as in an oil refinery. The weir 400 includes adrainage wall 410 that is produced using a drainage composition thatuses the following ratio of components:

-   -   1400 kg/m³ of 30 mm aggregate;    -   210 kg/m³ of cement;    -   35 kg/m³ of fly ash; and    -   0.5 kg/m³ of fibrous material.

The drainage wall 410 forms a dam. However, water 401 is allowed to passthrough the drainage wall 410 at a constant flow rate determined by theratio of components used in the drainage composition.

A filter material 420 is located over the drainage wall 410. The filtermaterial 420 is used to capture impurities that are located within thewater. A typical filter material is a geo-textile but other filtermaterials can be used. The filter material 420 is replaced after apredetermined period of time.

The weir 400 operates by allowing water to pass through the drainagecomposition. The water then must pass through the filter material 420where the impurities are captured.

FIG. 9 shows a paving block 500 having a face layer 510 and a drainagelayer 520. The face layer 510 is made from concrete whilst the drainagelayer 520 is made from a drainage composition that uses the followingratio of components:

-   -   1200 kg m³ of 25 mm aggregate;    -   250 kg/m³ of cement;    -   50 kg/m³ of fly ash; and    -   0.4 kg/m³ of fibrous material

The paving block 500 is produced pouring concrete into a mould to formthe face layer 510. Whilst the concrete is still wet, the drainagecomposition is pour on top of the concrete to form the drainage layer520. The paving block 500 is then allowed to dry.

The paving block 500 is integrally formed and has improved drainagecharacteristics, as water is able to pass through the drainage layer ofthe paving block.

It should be appreciated that various other changes and modificationsmay be made to the embodiment described without departing from thespirit or scope of the invention.

1. A drainage composition comprising: 1000 to 1500 kg/m³ of aggregate;100 to 350 kg/m³ of cement; 35 to 100 kg/m³ of fly ash; and 0.2 to 0.6kg/m³ of fibrous material.
 2. The drainage composition of claim 1wherein the size of the aggregate varies from between 10 mm and 75 mm.3. The drainage composition of claim 1 wherein different sizedaggregates are combined in the drainage composition.
 4. The drainagecomposition of claim 1 wherein the volume of aggregate to fly ash isapproximately 3:1.
 5. The drainage composition of claim 1 wherein thefibrous material is a synthetic fibre.
 6. The drainage composition ofclaim 5 wherein the synthetic fibre is a nylon fibre.
 7. The drainagecomposition of claim 5 wherein the fibre is between 19 mm to 50 mm long.8. The drainage composition of claim 1 wherein the drainage compositionis fabricated into blocks or panels.
 9. The drainage composition ofclaim 1 wherein sand is added to the composition.
 10. The drainagecomposition of claim 9 wherein the weight of sand is between 40 to 200kg/³.